I took the index with the words, converted the amount to binary, included three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to transform it to binary, added 3 zeros into the 8 digits with the binary and obtained 00000010011 which translates to 19 in https://cruxbookmarks.com/story19525497/ledger-seed-phrase-bip39-no-further-a-mystery